There have hitherto been known various thiazole derivatives, among which some compounds having a somewhat similar substituents to those of the present invention are disclosed in the following literatures.
JP-A-2-306916 discloses inhibitors for platelet adhesion comprising a benzazole compound of the following formula: ##STR3## wherein X is S or &gt;N--R.sup.3 (R.sup.3 is H, lower alkyl, etc.); R.sup.1 is halogen, cyano, cyano-substituted lower alkoxy, phenyl-alkyl having a substituent on benzene ring, substituted furyl-alkoxy, substituted pyrrolidinyl-alkyl, substituted amino, substituted amino-alkyl or -alkoxy, etc.; R.sup.2 is pyrrolyl having optionally alkyl substituent, thienyl, pyridylthio-lower alkyl, phenyl group which has optionally 1 to 3 substituents selected from lower alkoxy, lower alkyl, OH, halogen, or --O--Y--NR.sup.8 R.sup.9 (Y is lower alkylene, R.sup.8 and R.sup.9 are each H, lower alkyl, cycloalkyl, or both combine to form a nitrogen-containing 5- or 6-membered saturated hetero-cyclic group, or --NR.sup.10 R.sup.11 (R.sup.10 and R.sup.11 are each H, lower alkyl, substituted phenyl, or both combine to form a heterocyclic group). However, the benzazole compounds of this literature are significantly different from the thiazole compounds of the present invention in the substituents at 2-position of the thiazole nucleus. Besides, this literature does not disclose any compounds having protein kinase C inhibitory activities as in the present invention.
European Patent 318 084 (=U.S. Pat. Nos. 4,957,932 and 5,037,840) discloses that the benzoheterazoles of the following formula are leukotriene antagonists and inhibitors of leukotriene biosynthesis and are useful as antiasthmetic, antiallergic, anti-inflammatory and cytoprotective agents. ##STR4## wherein R.sup.1 is H, halogen, alkyl, etc.; R.sup.2 is alkyl, alkenyl, etc.; R.sup.3 is H or R.sup.2 ; R.sup.4 is H, halogen, --NO.sub.2, etc.; R.sup.5 is H, halogen, --NO.sub.2, etc.; R.sup.7 is H or alkyl; X.sup.2 and X.sup.3 are O, S, S(O), etc.; X.sup.4 is NR.sup.3, O or S; Z.sup.1 and Z.sup.2 are --CONR.sup.3 -- or --HET(--R.sup.3,--R.sup.5)--; and Q.sup.1 and Q.sup.2 are --COOR.sup.3, --CONHS(O).sub.2 R.sup.13, --CN, etc. However, these benzoheterazoles of this literature are essentially different from the thiazole compounds of the present invention in the substituent at 2-position of the azole nucleus. Besides, this literature does not disclose any compounds having protein kinase C inhibitory activity.
Some thiazole or benzothiazole compounds having similar chemical structure to the benzoheterazoles of the above European Patent 318084 are also disclosed in PCT publications WO 93/21168 and WO 93/21169 and therein it is mentioned that those compounds are useful as leukotriene antagonist, but these thiazole or benzothiazole compounds of these literatures are clearly different from the thiazole compounds of the present invention in the substituent at 2-position likewise, and further these literatures do not disclose any compound having protein kinase C inhibitory activity, either.